Thermostat Replacement: Slow Speed & Blinking?

the preheating lamp.

Hi!

I had the thermostat replaced at VAG last Monday. The temperature seems to be okay again, the turbo kicks in a bit earlier, and the car feels slightly more responsive (not much). However, last Tuesday, the glow plug light started blinking (only on Tuesday). I immediately made an appointment with VAG and will have the error codes read tomorrow (I don't have the money for an adapter yet). I would like to know if you can see any connections between these issues. The glow plug light blinked on the highway in traffic last Tuesday, and hasn't blinked since. Although, overall, the improvements I described above have occurred since the thermostat replacement, several attempts to accelerate on the A555 (no speed limit) were unsuccessful. Before the thermostat replacement, I could reach 190 km/h on a straight road, and 205 km/h downhill with a tailwind, according to the speedometer. Now, after the replacement, I can barely reach 180 km/h on a straight road, or just slightly above. The car is a Golf III with a 1Z engine, it's not chipped, and has approximately 105,000 km on the odometer.

Can someone perhaps come up with a rhyme for that?

Thank you in advance.
MisterX.

Hi,

Which thermostat was replaced? And why was it replaced?

hi!

I'm risking being called stupid, but I have no idea which thermostat was replaced! I read a thread on this forum that described a loss of power due to a faulty thermostat. According to that, the coolant temperature was around 70°C during driving. Since my Golf was also only showing 70 degrees (at most 90°C when I was stuck in traffic), I had it replaced by VW on a hunch (it was covered by the warranty, so it wasn't too expensive). Now, I'm actually reaching the correct temperature, but I'm experiencing the described side effects.

Does that help you?


Best regards,
MisterX.

It's likely that the workshop caused some collateral damage while installing the coolant thermostat.

In what way?

What could be the cause, and could it be related to the loss of power?

Hello,

It's either a coincidence, or the workshop messed something else up during the installation.

Best regards, Rainer.

Hi!

The error memory scan revealed:

Brake pedal monitoring - implausible signal - intermittent.

'Since the glow plug light only blinked once, the mechanic suggested I should continue to monitor it. He believed the loss of power indicated a faulty lambda sensor (oxygen sensor). Because it's covered by a used car warranty, it shouldn't be too expensive, so I'll have the lambda sensor replaced next Saturday.'

Sure, here is the translation of the text from German to English:

'Hello,'
misterx

Hi X,

The switch on the brake pedal can be adjusted. -> Search function.

Greetings, Rainer.

Hi!

'Today, I did the diode test related to the lambda sensor! As far as I can tell, it seems to be accepting the gas better, but it still doesn't go faster than 180 km/h. Do I absolutely have to disable the EGR valve if I use the diode?'

Hi everyone,

I'm experiencing the exact same problem - the coolant temperature sensor is defective. Since then, the maximum speed is approximately 175 km/h, whereas it used to be at least 185 km/h (Sharan TDI PD 85kw automatic). Acceleration is sluggish above 160 km/h.

My VW workshop is facing a puzzle. The mass airflow sensor (MAF sensor) has been replaced, but there's been no change.

I would be happy if this thread picked up momentum again!

Heiko.